I've been reading about the wonders of extruded polystyrene insulating tiles, and how they could help to make the UK's ancient housing stock less wasteful of energy. Climapor, one of many manufacturers, says that their 6mm tiles have the same insulating properties as 117mm of brick or 360mm of concrete. So i was wondering whether a cheapish 3d printer could produce these tiles. Obviously they'd have to be small, but I'm picturing a rather thrilling panacea for plastic waste....you build cheap open source plastic recycling machinery courtesy of preciousplastic.com, snaffle a basic 3d printer from somewhere, put them in a coffee shop or some other spot which is convenient for the local populace...people wander in with plastic packaging, recycle it into filament, print a tile or two...hexagonal ones would be easy to work with and look nice...and they gradually cover their walls with their refuse.

I can't find any detail about the structure of these tiles. No idea whether the extrusion process is something done by millions of pounds worth of specialist factory equipment, or whether a 3d printer head could manage it.

As for fire risks, ISTR that ceiling tiles were regarded as lethal when fixed with blobs of glue in the corners, because of the air pockets created. You're supposed to apply glue to the whole surface of the tile.

I haven't found out whether extruded foam is the same as expanded foam, or Styrofoam, or whatever. There are oodles of foam insulation products for building purposes. But the subject is a mystery to me.

Sprayfoam insulation has been used for a long time (couple of decades maybe) for many niche uses. Very popular in boats. It isn't a styrene and is fire-resistant. I find it hard to believe that a 3-D printed tile would exceed the performance of sprayfoam.

Trouble with reusing plastic is that most plastic is flammable, extremely flammable. Not great stuff to be using as insulation.

I am not convinced about polystyrene at all. Spray in poly bead insulation was used heavily some years ago as cavity wall insulation and people are now having to remove the product with huge difficulty and expense where the material has slumped within the cavity, this leaving the rest of the structure uninsulated and producing odd differential thermal gradients. How cavity bats will fare remains to be seen. Thermal imaging surveys may reveal the answer. Surface spread of flame and melting/dripping have been touched upon. Anyone who has seen the old Building Research Establishment (BRE) fire videos where untreated polystyrene tiles were a factor will be product averse. (Kings Cross shudder). Even with retardent, the areas of application are defined and the material cannot be used on fire escape runs etc. People also do silly things like painting tiles with gloss paint which removes all of the benefits of retardent. So for me its a no no, there are good alternatives. Recyled glass being one of them.

Do you think solid wall insulation for older buildings will have to be the norm if the UK is to reach zero emissions? If so, how's it going to be done? It's such a massive task, and external insulation and internal Celotex boards both have so many disadvantages.

As usual the UK lags behind. Quite how the UK will achieve its stated objectives given the state of the housing stock, lord knows. Perhaps this is what Hammond was banging on about. I can't remember now but was not BedZed supposed to be a demonstration project for zero emissions? Compare this with the many, many thousands of Victorian terraced speculative mass build terraces still in use (not to say they are not good housing) and the crap put up in the 1960s thank you Dick Crossman, (not a political point) the scale of the problem becomes self apparent. If public investment continues along the everyone in London has £2300 a year spent on them and the rest of the country has £300 a head then it is nonsense.

I spent four years in the civil engineering industry and it is disgraceful how the clients have rejected initiatives like recyclable buildings. All buildings have a shelf life, so it is logical to design them such that they can be sustainably decommissioned and recycled. Instead every client under the sun insists on bespoke in situ designs made of concrete and rebar which are hugely energy intensive to deliver and demolish. Clients just don't care about the long run so long as there is a swish pile of bricks to cut a ribbon in front of.

I am not convinced about polystyrene at all. Spray in poly bead insulation was used heavily some years ago as cavity wall insulation and people are now having to remove the product with huge difficulty and expense where the material has slumped within the cavity, this leaving the rest of the structure uninsulated and producing odd differential thermal gradients.

I'm dithering about getting this done to our 1970 bungalow. The walls in the extension are nice and warm (kingspan) but you can feel a massive difference when you touch an original wall (no insulation). The problem is though the inside walls are breeze blocks the outside is random stone and the cavity wall people dont recommend blown foam etc as the unevenness of the cavity stops it getting everywhere. They recommend poly beads. These days apparently they use some kind of adehsive with them that sets and stops them slumping (or running out of any convenient hole).

Quite how the UK will achieve its stated objectives given the state of the housing stock, lord knows. Perhaps this is what Hammond was banging on about.

Replacing the UK's domestic energy demand for methane with heat pumps running on a de-carbonised grid and hydrogen in the gas pipes from non carbon sources, the latter being a straight reversal of the high speed gas project in the 60"s. That gets round having to insulate and draft proof to the nth degree.

Insulating cavity walls as a peculiarly UK problem as they aren"t really found anywhere else as they were a cheap, simple and material saving answer to constructing rain resistant masonnary walls with a lack of skilled labour in Victorian times.

Blown bonded expanded polystyrene (EPS) beads is best for block/stone facing as it will resist penetrating rain (more likely with a stone facade) from crossing the cavity. Blown fibre gets soggy in such applications and PU foam presents a risk of water penetration at the joins between the individual globs of foam meet as it cannot be injected as a continuous mass.

Any plastic insulation on a potentially exposed element of a building, particularly a dwelling is basically a no no, Grenfell just being the latest in a long series of tragic errors probably starting with the EPS tiles of the 60's.

Build tight (airtight), ventilate right (MVHR), insulated foundations (the perfect application for EPS) avoid heat bridge and aim for an insulation package with a high decrement delay (~12 hours).

Trouble is UK house buyers are grossly uninformed about what a good house should be and therefore developers face no pressures to change their offer as they are providing what the customer wants and can't build enough of the crap fast enough to keep up with demand.

Hope this doesn't suffer hydrolysis and disintegrate like PU foam-soled shoes I have owned! It might be a pain to chuck half the shoes in my cupboard but it's trivial compared to trying to deal with a similar process in a wall cavity.

Quite how the UK will achieve its stated objectives given the state of the housing stock, lord knows. Perhaps this is what Hammond was banging on about.

Replacing the UK's domestic energy demand for methane with heat pumps running on a de-carbonised grid and hydrogen in the gas pipes from non carbon sources, the latter being a straight reversal of the high speed gas project in the 60"s. That gets round having to insulate and draft proof to the nth degree.

Insulating cavity walls as a peculiarly UK problem as they aren"t really found anywhere else as they were a cheap, simple and material saving answer to constructing rain resistant masonnary walls with a lack of skilled labour in Victorian times.

Blown bonded expanded polystyrene (EPS) beads is best for block/stone facing as it will resist penetrating rain (more likely with a stone facade) from crossing the cavity. Blown fibre gets soggy in such applications and PU foam presents a risk of water penetration at the joins between the individual globs of foam meet as it cannot be injected as a continuous mass.

Any plastic insulation on a potentially exposed element of a building, particularly a dwelling is basically a no no, Grenfell just being the latest in a long series of tragic errors probably starting with the EPS tiles of the 60's.

Build tight (airtight), ventilate right (MVHR), insulated foundations (the perfect application for EPS) avoid heat bridge and aim for an insulation package with a high decrement delay (~12 hours).

Trouble is UK house buyers are grossly uninformed about what a good house should be and therefore developers face no pressures to change their offer as they are providing what the customer wants and can't build enough of the crap fast enough to keep up with demand.

Tod28, what about internal insulation of solid walls in older buildings - i.e. vast swathes of London, Manchester, Liverpool, Birmingham etc. I have no relevant background/training, but it seems to me that an awful lot of these buildings won't be externally cladded for eons because of a long list of reasons:

- landlord won't pay and doesn't care- owner-occupier won't pay and doesn't care- buildings are divided into flats and the occupants won't come up with a shared plan to pay a contractor- the disruption and expense of scaffolding, dust, noise etc are a huge disincentive. People will shrug their shoulders and wait for nanny state to come up with a plan. But we are cursed with a barely functional government which won't borrow/invest- cladding will completely change the look of the buildings. Owners and planners will object

So the reason I got excited about recycled plastic tiles is that occupants can insulate gradually at almost no cost. Hardly any disruption. Landlords needn't even be involved. Thin plastic tiles allow skirting boards, carpets, electrical fittings, cornices and so on to be left as is - the tiles can just be trimmed with scissors to fill in the gaps. The wall ends up only 80 or 90% insulated, but perhaps that's enough? And the building can still breathe a bit through the untiled areas, reducing condensation/mould issues which could be very expensive and disruptive to fix...I imagine they require new ducts or air bricks or an electricity-consuming dehumidifier going all the time.

Recycled plastic tiles have many disadvantages - they're flammable, ugly unless painted, the recycling and 3D printing uses lots of energy and emits toxic fumes. Can you think of better ways, or am I really just barking up wrong tree?

A question with insulating anything in a cold climate is; where is the dew point?

The dew point is the point at which condensation will form. In a badly-insulated house, with cold walls, it is often on the inner surface of the walls (particularly when there is poor air circulation and the air in the house is humid). Condensation forms on the walls and mold grows. This is really common in cheap rented accommodation, when people dry their clothes on racks in the house, keep the windows shut (to keep heating bills down), then complain when mold grows everywhere!

If your external wall isn't insulated in some way, and you plaster it with some insulating tiles (with gaps), I think you will end up with a cold wall, warm air passing through the gaps in the tiles, and condensation forming on the wall. A engineered solution to this might be to use a membrane (Tyvek or similar) between the wall and the tile, with a small gap. That would require you to cover the entirety of the inner wall with membrane and tile though.

Tod28, what about internal insulation of solid walls in older buildings

Thermal bridging where internal structural elements meet the outer skin - eg bracing walls and floors is the big problem. As Mr Charly commented, those parts of the structure still connected to the external element without a thermal barrier will remain cold and not only act as heat loss points but will provide surfaces which remain below the dew point temperature for condensation/mould. This is also a pertinent point with retro-fitted external insulation at foundations - if the insulation is not carried down below ground level the base of the internal wall skin will lose heat through the founds with resulting condensation/mould.

On the subject of pouring EPS beads from the roof space down the cavity, it doesn't get the beads below window sills etc and the only force distributing the beads is gravity. As EPS beads are very light the packing density from gravity alone is very poor and you may also be combating moderate air flows in the cavity during installation blowing the beads back at you and there is a risk of beads hanging up in the cavity leaving gaps in the insulation.

On the subject of pouring EPS beads from the roof space down the cavity, it doesn't get the beads below window sills etc and the only force distributing the beads is gravity. As EPS beads are very light the packing density from gravity alone is very poor and you may also be combating moderate air flows in the cavity during installation blowing the beads back at you and there is a risk of beads hanging up in the cavity leaving gaps in the insulation.